function [ RET ] = gaussian (X)

FIR_GUASSIAN = [2 4 5 4 2; 4 9 12 9 4; 5 12 15 12 5; 4 9 12 9 4; 2 4 5 4 2] .*(1/159);

RET=conv2(double(X),FIR_GUASSIAN,'same');

[height width] = size(RET);

RET(1:height,1) = RET(1:height,2);
RET(1:height,width) = RET(1:height,width-1);
RET(1,1:width) = RET(2,1:width);
RET(height,1:width) = RET(height-1,1:width);
